Friday, February 1, 2013

Glacier National Park – Montana


The northern tip of the Rockies in Montana became the United State's tenth National Park in 1910. Glacier National Park contains more than a million acres (about 4000 square kilometers) of forest, lakes, meadows – but most of all, mountains. Not just any mountains, but oh-my-god mountains, the views of which take-your-breath-away-mountains. These rugged, glacially-carved massifs so impressed the native Americans who first lived there that they called them “the backbone of the world.”

Mountains are not made in any single geologic event. In short, this is their story:

--The rocks that the mountains of Glacier Park are built are very, very old. They belong to the Belt Supergroup, a Proterozoic series of sediments that eroded from an ancient continent into an immense oceanic basin from about 1.5 billion to 800 million years ago. These rocks are famous for their stromatolites (blue-green algae colonies) and ripple marks, raindrop imprints and mud cracks that look just like those that can be found in fresh mud along any river today.

--About 170 million years ago, the rocks of the Proterozoic began to be thrust over much younger rocks during the earliest stage of the birth of the Rocky Mountains: the surface over which these rocks were thrust is the Lewis Fault, visible on many of Glacier’s tall mountains.

--The major phase of mountain building in the Rockies began in the late Cretaceous, about 80 million years ago, and lasted until about 40 million years ago. This is the Laramide Orogeny, caused essentially by the North American Plate “running over” another tectonic plate (the Farallon Plate which no longer is found on the earth’s surface) with help from the pushing of the rapidly spreading Pacific plate. (If this sounds complex, forgive me non-geologist readers, it is – even for geologists!)

--Since the Laramide Orogeny, the entire region has been rising, causing the uppermost crust to stretch, resulting in up-faulted blocks of mountains and down-dropped valleys.

--With rocks and mountains in place, the final glorious embellishment to the terrain of the Park was made by (not surprising given its name) glaciation. In 1850, 150 glaciers were catalogued in what was to become the park area: today, 26 remain, and these are the remnants of far larger glacial systems that literally carved the mountains in the latest ice age, 12,000 to 10,000 years ago. One of these ancient glaciers carved the valley that today contains Lake McDonald, 15 kilometers in length and the largest lake in the park. It is estimated that the glacier that scoured the Lake McDonald valley was about 670 m thick.

In today’s geography, Glacier Park stands on the continental divide, or rather, the continental “trivide” since waters from Glacier’s mountains flow to the Pacific, the Atlantic, and into the Arctic Ocean past Hudson Bay. In 1932, Glacier Park and adjoining Waterton Lakes National Park across the Canadian border were designated the Glacier-Waterton International Peace Park.

Now of late, I have coined to term “Geowonder” to refer to an area that, literally, is defined by the reaction of a visitor’s first view of an area as the car turns a corner – suddenly the visitor is silent, then he/she gulps, then – “wow!” Places on the earth with views that have the power to take your breath away are and leave you speechless, by this definition, are --geowonders.

Wow! As such, Glacier Park is… the very definition of a Geowonder!


I don’t think it’s possible for a photo from Glacier to be anything less than a wow!, but I’ve downloaded this one of Swiftcurrent Lake from:
http://www.worldfortravel.com/2011/11/10/beautiful-glacier-national-park-montana-usa/swiftcurrent-lake/

More geo-wondrous information on Glacier Park at:
http://www.nps.gov/glac/index.htm
http://visitmt.com/national_parks/glacier/
http://www.glacier.national-park.com/
http://bcpg.geoscienceworld.org/content/25/4/736.abstract



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